1. Field of the Invention
The present invention relates to an object, a method, or a manufacturing method. The present invention relates to a process, a machine, manufacture, or a composition of matter. In particular, one embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a storage device, a driving method thereof, or a manufacturing method thereof. In particular, one embodiment of the present invention relates to a power storage device and a manufacturing method thereof.
Note that a power storage device in this specification refers to every element and/or device having a function of storing electric power.
2. Description of the Related Art
In recent years, a variety of power storage devices, for example, secondary batteries such as lithium-ion secondary batteries, lithium-ion capacitors, and air cells have been actively developed. In particular, demand for lithium-ion secondary batteries with a high output and a high energy density has rapidly grown with the development of the semiconductor industry, for electronic devices, for example, portable information terminals such as mobile phones, smartphones, and laptop computers, portable music players, and digital cameras; medical equipment; next-generation clean energy vehicles such as hybrid electric vehicles (HEVs), electric vehicles (EVs), and plug-in hybrid electric vehicles (PHEVs); and the like. The lithium-ion secondary batteries are essential as rechargeable energy supply sources for today's information society.
In a storage battery that utilizes the reaction of carrier ions, such as a lithium-ion battery, the volume of an active material might be changed by charge and discharge process. For example, it is known that the interlayer distance of graphite increases from 0.336 nm to 0.370 nm as disclosed in Non-patent Document 1 (see Non-Patent Document 1, pp. 333-334).
As disclosed in Patent Document 1, for example, the shape or volume of an alloy-based material such as silicon might be changed by repeated charge and discharge cycles.